Residents are being urged to drink plenty of water and schedule outdoor activities during cooler times of the day as hot and humid conditions are expected to stick around, possibly until the middle of this week.
Environment Canada issued a heat warning for several areas of southwestern Ontario, including Sarnia-Lambton.
Forecasters said daytime temperatures may reach up to 32 Celsius with humidex values in the high 30s and low 40s.
Nighttime will offer little relief as temperatures are expected to hover around 21 C. Hot and humid weather may result in deteriorating air quality.
Residents are also being reminded to never leave people or pets inside a parked vehicle.
Cooler temperatures are expected near Lake Huron.
